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I need some help. I am getting this lumps that show up. It looks like I'm printing great until the effector needs to start retracting and moving to a different spot. I am printing with PETG at 240deg C, E3D Titan Aero extruder, Anet A8.
I have had something similar.
Does this occur when the hotend is travelling through an arc?
I noticed this when I was doing prints, there would be "microblobbing" but only on curved sections. I put it down to the RAMPS board not having sufficient processing power to calculate all the paths and pausing for a very short period. The "ooze" at this point caused a small blob.
I think this was confirmed when I slowed print speed right down (20mm/s on a delta, it can easily move at 120mm/s or faster), which alomst completely eradicated the issue.
In the end I took the LCD display off completely and just use octoprint as the interface. The small amount of processing needed for the display compensates for the blobbing which is much reduced and I have been able to turn up the print speed again. I suppose I could use a more powerful controller board too.
This might be a red herring, but its worth having a look at.
did you try to retract in higher speed? PETG tends rather strong to pull strings - I could already say that.
PETG is always fairly prone to leaving strings and blobs, but you can usually make it reasonable by using a long and fast retraction. I'm using 6.5mm at 65 mm/s for it and only get some fairly minor strings, but different printer and extruder so you might need different numbers.
If that doesn't help, dropping the temperature a little might. PETG does do well at higher temperatures, though, so that 240C sounds right unless you're printing slowly.
Hope this helps. I had to take a screen shot of a video.
It's hard to see in your photos .. so I will assume you are seeing random "globs" of plastic? I've had that problem, for me it was caused by PETG accumulating on the print nozzle, until a large amount would come loose. The solution for me was to REDUCE the extrusion flow rate .. PETG is VERY touchy in regard to flow rate, .. you have to play with this and dial in your flow rate to an optimum level .. my flow rates with PETG typically are lower than for PLA ... 2 to 5% lower. Watch it while printing, if you see plastic accumulating on the nozzle, dial down the flow rate ... I have even resorted to removing that plastic while printing, a piece of filament actually works well for that, nozzle plastic will stick to the filament piece, or try something like a large tooth pick. Good LUCK.
Can we get a better picture?
This ones a bit blurry, hard to see exactly.